Researchers at the science and technology forum at the World Summit on Sustainable Development in Johannesburg have called for a new "cold war" on climate change.

Summit facts

60,000 delegates from 140 countries Estimated spending on travel: $2.2m Estimated fuel used: 36 million litres Estimated waste for 10-day summit: 600-700 tonnes Estimated production of greenhouse gas CO2: 300,000 tonnes Source: World Conservation Union

They said urgent action was needed to combat damage humans have done to the world's climate, atmosphere and biodiversity.

The call comes after delegates reached agreement on ways to tackle the world's fisheries crisis.

US researcher Berrien Moore said that political interests had dominated research agendas on climate change for too long.

He added that the irreversible changes humans had wrought on the environment, including the felling of large swathes of forests, meant that policy makers could no longer ignore the dangers.

"The issues are there and we're not going to be able to duck them," he said.

Fisheries deal

The fisheries deal - the first substantial one reached at the summit - envisages restoring most of the major global fisheries to commercial health by 2015.

At the insistence of the US, the agreement stipulates that replenishment of stocks should happen "where possible".

But the agreement is also seen as a defeat for the US because it does specify a target and a timetable.

The Americans had argued that, instead of new targets, countries should try to keep to existing commitments.

The UN says more than 25% of the world's fisheries are over-exploited, 50% are being fished to their full capacity and 75% need immediate action to freeze or reduce fishing to ensure future supplies.

Another section of the agreement provides for the establishment of marine protected areas across the planet by 2012.

Targets set

This is the first agreement reached which has a specific date for completion.

It will be incorporated in the action plan at the end of the summit.

40,000 delegates are attending the 10-day summit

The BBC's Alex Kirby in Johannesburg says the agreement has eased the dour mood that marked the opening of the World Summit.

Agreement is also said to be close on about 50 specific targets for improving the environment, preventing loss of biodiversity, education for women and aiding poor countries, Canadian officials told French news agency AFP.

Activists had complained that agreement on important issues was being stifled by the interests of big business.

But green activists scored a small victory on Tuesday by having the issue of big business accountability over the environment put back in the summit's draft action plan.

The re-proposed text calls for a "global reporting initiative" in which businesses are encouraged to report annually on activities that affect the environment.

Activist complaints

Public discussions on agriculture began on the second day of the summit.

	Six of the world's hungriest countries are in sub-Saharan Africa Nearly 30% of the world's population suffers from malnutrition There is 40% less arable land worldwide than there was in 1970 Human activities have degraded 15% of the world's land In-depth guide to the world's growing food crisis

Observers say agreement on agriculture will prove difficult, as developing countries say that the Europeans and Americans are not prepared to discuss reform of the world trade system and the reduction of subsidies to agriculture.

They also said the broad agenda of this summit creates almost endless scope for disagreements and is making consensus difficult to achieve.

Delegates from the European Union have complained that their American counterparts are not prepared to sign up to specific targets on issues such as energy and water.

At the summit opening on Monday, South African President Mbeki urged delegates to come up with practical ways of tackling poverty and ending a world order based on the "survival of the fittest".